FIG. 26 is a schematic diagram illustrating the structure of a power semiconductor module.
A power semiconductor module 50 includes a frame 51 which is made of a polyphenylene sulfide (PPS) resin and a terminal 53 that passes through the frame 51 and is buried in a first step portion 52 of the frame 51. The power semiconductor module 50 further includes a second step portion 54 which is formed in the rear surface of the frame 51 and a circuit board 56 which is fitted to the second step portion 54 and is fixed by an adhesive resin 55. The power semiconductor module 50 further includes a semiconductor chip 57 which is soldered to the circuit board 56, a wire 58 which connects the semiconductor chip 57 and the terminal 53 using ultrasonic bonding, and a sealing material 59 which is filled in the frame 51. The circuit board 56 includes a metal plate 56c which is made of, for example, aluminum, an insulating plate 56b which is made of, for example, an epoxy resin and covers the metal plate 56c, and a circuit plate 56a which is formed on the insulating plate 56b. 
The surface of the first step portion 52 of the frame 51 is flush with the surface of the terminal 53. The terminal 53 is formed by cutting off an unnecessary portion of a lead frame. The frame 51 functions as the resin case. In addition, the terminal 53 is fixed to the frame 51 by integral molding.
FIG. 27 is a diagram illustrating only the frame and the terminal in the enlarged view of FIG. 26 illustrating a portion B.
The adhesion between the rear surface 53a of the terminal 53 which is integrally molded and the bottom 52a of a buried portion of the first step portion 52 in the frame 51 is low. In addition, in some cases, as illustrated in FIG. 27, the terminal 53 buried in the first step portion 52 comes off the bottom 52a of the buried portion of the first step portion 52 due to the difference between the thermal expansion coefficients of the terminal 53 and the first step portion 52. In this state, during wire bonding, ultrasonic vibration is not effectively transmitted to the terminal 53, which makes it difficult to perform strong wire bonding. As a result, the wire 58 peels off from the terminal 53.
As a method for solving this problem, Patent Document 1 discloses a technique in which a terminal with an inverted T-shaped cross-sectional structure is buried in a case, and a case member fastens and fixes the terminal.
Patent Document 2 discloses a technique in which a protruding portion is provided in a case and is pressed against a terminal from the upper side to fix the terminal.
Patent Document 3 discloses a technique in which a pin is inserted into a through hole that is provided in a portion of the rear surface of a case below a terminal and lifts and fixes the terminal.
Patent Document 4 discloses a technique in which a terminal is bonded to an anchor plate and the anchor plate is fixed to a case. The anchor plate and the case are made of the same material and the surfaces of the anchor plate and the case are melted so that the anchor plate and the case are integrated with each other. In this way, the terminal is firmly fixed.